1. Field of the Invention
This invention relates to apparatus used to power flying vehicles such as aircraft, aerospacecraft, missiles and rockets. The improved engine apparatus provides a combination of ejector and other engine elements to enable efficient engine performance over a wide range of velocity.
2. Description of Related Art
There are currently disclosed in the literature many techniques for construction of ramjet engines and for use of injectors with various engines including ramjet engines to form an ejector to operate cooperatively with the ramjet cycle of the engine. However, no practical, operational ejector ramjet engine for engine operation from zero velocity to hypersonic flight appears to have been developed other than that disclosed in U.S. Pat. No. 5,946,904 by the same inventors as this improved ejector ramjet engine.
The ejector ramjet engine offers advantages relative to the conventional ramjet engine such as sea level static thrust and engine thrust at low level flight speeds. For a given flight condition the ejector ramjet can provide larger engine thrust than the conventional ramjet engine. This may be particularly advantageous during flight vehicle transonic acceleration and hypersonic/high altitude flight conditions where ramjet thrust may not satisfy vehicle requirements. Improved combustor performance due to higher pressure and temperature levels in the combustor can also be achieved which allow combustor operation at higher flight altitudes than possible with a ramjet engine. The ejector ramjet also allows injection of excess oxidizer to enrich the oxidizer in combustion to further increase thrust.
Various methods for augmenting jet engines or ramjet engines have been proposed as typified by the disclosures in U.S. Pat. No. 5,129,227, granted Jul. 14, 1992 and U.S. Pat. No. 5,327,721, granted Jul. 12, 1994. In the case of U.S. Pat. No. 5,129,227, a fuel rich injectant is introduced into the mixing zone of a duct to form an ejector. The composition or equivalency ratio and the temperature of the injected gas are controlled to prevent combustion in the mixing duct. The velocity flow along the wall of the duct is also controlled by the structure of the injector to aid in preventing propagation upstream of the combustion from the combustor.
With regard to U.S. Pat. No. 5,327,721, a rather complex system to improve on the entrainment of fluid as disclosed in related art is presented. An injector is modulated to alternate the direction of the primary fluid jet in an ejector to entrain secondary fluid. The oscillation of the primary jet provides energy exchange between the primary and secondary fluids in the propulsion duct in a substantially non-viscous fashion.
Techniques for mixing fluids or hypermixing are exemplified by U.S. Pat. No. 4,257,224, granted Mar. 24, 1981 and in the article Journal of Aircraft, Volume 9, No. 3, March 1972, Pages 243-248, by Richard B. Fancher, entitled xe2x80x9cLow-Area Ratio, Thrust-Augmenting Ejectorsxe2x80x9d. U.S. Pat. No. 4,257,224 presents a method and apparatus for improving the mixing of two fluids using an active element in the vicinity of the beginning of the mixing region. Oscillations are induced in the two fluids about an axis substantially normal to the mixing region flow axis.
The article by Fancher discusses various hypermixing techniques and includes the disclosure of an experimental ejector design and setup. The disclosed design uses a primary nozzle, which is segmented into 24 elements 1xc2xd inches long. Each element gives its exiting mass a velocity component normal to both the nozzle""s major axis and the fluid flow axis; the direction of this lateral velocity component was alternated from element to element.
An embodiment of the present invention uses a combination of a variable geometry ramjet engine, an ejector system and an air liquefaction system integrated into a highly efficient, lightweight propulsion system. The inlet has been designed to match the operational profile of a hypersonic air breathing vehicle. For low speed operation the inlet cowl closes to a point that minimizes drag. Air for the air liquefaction system may be ducted through a movable flap inside the engine inlet and the resulting liquid air is either used in the ejector system or may be stored for use at a later time. For high speed flight the inlet cowl opens to its maximum position to capture the maximum amount of air the engine can use; thus maximizing thrust.
An injector assembly having slot nozzles with alternating orientation relative to the longitudinal axis or fluid flow axis of the engine is located at the upstream end of the mixing section. There may be provision to allow an external or internal, relative to the ramjet engine, combustion chamber to create the gas for the injector assembly. For the ejector ramjet engine to function with vehicles that operate over a velocity range of zero to hypersonic, a liquid air cycle process may be used with the injectors that uses the cooling properties of liquid hydrogen stored on the vehicle to liquefy environmental air as the oxidizer for the injector combustion chamber, or a combination of a liquid air cycle process and stored liquid air at initial zero and low velocities. By storing excess liquid air it may be used to augment the air flow received in the inlet when the altitude of the vehicle is such that the air flow received at the inlet is not of sufficient pressure to support combustion in the combustor. Collection and storage of liquid air may also be used at other times to provide low speed operation such as loitering or circling capability during a landing approach and a subsequent power on landing.
The present invention involves an apparatus for an ejector ramjet propulsion system or engine to operate over the range of velocities from zero to hypersonic. Also, the ejector ramjet engine may operate from altitudes of sea level to greater than 150,000 feet.
Other embodiments of the invention include application of the injector technology to augment the flow path of jet engines such as turbojet, turbofan, turbo ramjet, turbo scramjet, supercharged ejector ramjet and the like engines.
In accordance with the description presented herein, other objectives of this invention will become apparent when the description and drawings are reviewed.